Cyanides photochemical generation

Vife have extensively studied (10) the photoinduced catalytic system (Figure 2) which is based upon the photochemical generation of cyanide ions from various cyanometa I lates, especially from octa-cyanomolybdate(IV) aod octacyanotungstate(IV) ions. Upon photolysis both compounds form cyanide ions with relatively high quantum yields. Cyanide Sons may act as a catalyst for the dimerizat ion of appropriate heterocyclic carb-2-aldehydes to enediols. Since this photocatalytic system has proved to operate also in solid layers, it may be used for an unconventional photographic process (11,12). 

Photolysis with visible light, DAP " TMSCN. The photochemical reaction generates an iminium ion that is trapped with cyanide."... 

Like most photochemical reactions, benzylic fragmentation has been known from the beginning of the twentieth century. The photoinduced cleavage of triphenylmethylcarbinol has been noted by Gomberg in Ann Arbor in 1913 [1] and the generation of triarylmethyl cationic dyes from their leuco form by Lifschitz in Zurich in 1919 [2]. A solution of the colorless derivative obtained from p-rosaniline and cyanide became colored in a few seconds when exposed to an iron arc lamp (Sch. 1, old and new notation). 

The photochemical reactions of naphthalene and phenanthrene with hydroxide and cyanide in aqueous acetonitrile to give substitution products have been studied by flash photolysis and fluorescence spectroscopy.Evidence for the generation of the arene radical cation was obtained. Similarly, the conversion of 1,4-dimethoxybenzene to 4-cyanoanisole by ultra-violet light irradiation of slurries of tungsten oxide or titanium oxide in aqueous acetonitrile has been shown by flash photolysis to involve the intermediacy of the dimethoxybenzene radical cation. 

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